Wanted to take a moment to introduce myself to the board and to ask a question. I just recently acquired my first m5 - a 2006 silverstone with several Dinan goodies- after having many m3's (still have my e30 m3) and it is a fantastic car - cant wait to spend even more time behind the wheel! However, in the working on two months I have had it, it seems that an electrical issue has come up and I would appreciate some feedback and suggestions on what may be the culprit.
As a disclaimer: yes, I did search the board and found many things to be helpful but would appreciate some further clarification or to tell me if I missed something.
Here is what went on:
Got the car - drove it for weeks - no problem.
One day, stuck in traffic on a hot day, trans warning light comes on. Then goes away. No issues after that.
Park car one night and I left the running lights on (stupid mistake) came out in the morning - dead battery.
I read about having the battery coded and what battery to get. Picked up a battery to drive it to the dealer (nearest being about 30 minutes awa) to have it coded. Plugged it in and the car started up fine but threw warning lights for everything; edc,trans,brakes, flat tire, etc. logic tells me that there is now way all of these mechanical systems failed simultaneously sittin in my driveway. So I drive it down to the gas station and it all goes away - read on here about the car resetting - great, all is well,
I then decided to take it to a dealer ~2 hours away as I know many of the guys there to have it coded and checked out. When I was just about there, all of the warnings came back. They looked at the car the following week - said the battery was fine - cleared the codes and drove it and it was all good. Great. Picked up the car and all is well.
Started driving it yesterday in ~100 degree heat and the high emissions warning came on. I read on here that can be caused by changes in the ambient temp and it went away with no other problems so all was well.
Started to drive with my wife to visit some family this weekend and again got stuck in traffic in high heat. The a/c started cutting out and then it started throwing more warning messages for everything again. Started it up this morning in cooler weather no problems. Drove it again for a little bit and all of the warnings came back and this time it flashed the battery warning - flashed that last time before the battery was coded. The speedo and cluster also freaked out and the idrive also flickered on and off (again, like last time).
So now I am back to square one....
I ruled out the following:
Battery connections: just done by BMW and had the ground wire recall done.
Battery: it's brand new, and coded.
All systems failing: based on my readings here and my experience with cars in general, I highly doubt everything broke at once.
My suspicions for the problem:
Alternator: it's not charging the system properly and it is other deficient or over loading the system and thus shutting things down.
Main relay: this is apparently located in the engine bay and is a solid state resistor (which does not like heat) and these problems seem to happen in high heat situations or when many accessories are run at once.
Fuse/other relay: there may be a common point or some type of redundant protection in the system that is either broken or failing that I am not aware of.
So after all of this - what do you folks with m5 experience think the issue may be? I love the car, and just want to be able to drive it! Thank you all in advance for your thoughts and I look forward to being part of the board!